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Determination of Frontal Offset Test Conditions Based on Crash Data
Published May 31, 1998 by National Highway Traffic Safety Administration in United States
This paper reports on the test procedure development phase of the agency''s Improved Frontal Protection research program. It is anticipated that even after all cars and light trucks have air bags for drivers and front seat passengers there will remain over 8,000 fatalities a year and over 100,000 moderate-to-severe injuries. This research program will address these injuries/fatalities through development of crash tests with impact conditions not currently addressed by FMVSS No. 208, development of additional or more appropriate instrumentation and injury criteria on the test surrogate, and evaluation of other sizes of test surrogates.
An analysis of crash data is presented using the National Automotive Sampling System (NASS) and the Fatality Analysis Reporting System (FARS) for fatality counts. The population is drivers in frontal collisions with air bag restraints. Using NASS, frontal impact modes are grouped into general "test" conditions which will best represent the real-world impact environment. These general test conditions include full barrier, left and right offset, and other impact modes. Using these general groupings of impact conditions, the analysis further assesses degree of overlap and impact direction to determine more specifically which crash conditions result in highest injury/fatality to drivers with air bags. Injury/fatality risk is also assessed by driver size and body region, with a more detailed analysis of leg injuries. Finally, a preliminary benefits analysis is presented for a future frontal, left, offset test procedure.
A test procedure has been developed, and is reported on in a separate paper. Collinear and oblique, offset, frontal crash testing, at different widths of overlap, has been conducted with several current model, "target" cars into a standard "bullet" car at closing speeds of about 110 kph. Dummy injury measurements and structural responses provide a basis for determining which impact conditions produce the most severe environment for occupants with air bags. It appears that the oblique impact with over 50 percent overlap produces the most severe responses on the "target" car. Development of this impact configuration into a potential frontal test procedure has been completed using a moving deformable barrier (MDB).